Purines and pyrimidines

Question 1

Question 1
1.
A researcher wants to develop a method for labeling purines with 15N for use in future spectroscopic studies. Purine synthesis will be done using the enzymes necessary to synthesize purines via de novo pathway. Which starting material should be labeled with the heavy nitrogen in order to maximize 15N incorporation in purines?

Answer

A. Aspartate, Glycine, and Glutamate

B. Asp, Gly, and N5-formimino tetrahydrofolate

C. Glutamine, Glycine, and Aspartate

D. Asparagine, Glutamate, and Glutamine

E. Asparagine, Glycine, and Glutamate

Answer 1

C. Glutamine, Glycine, and Aspartate

Gln amide contributes N3 and N9

Gly contibutes C4, C5, and N1(7)

Asp contributes N7 (1)

N10 formyl-FH4 contributes C2 and C8

CO2 contributes C6

Question 2

Question 1
1.
A researcher wants to develop a method for labeling purines with 14C for use in future spectroscopic studies. Purine synthesis will be done using the enzymes necessary to synthesize purines via de novo pathway. Which starting material should be labeled with the radioactive carbon in order to maximize 14C incorporation in purines?

Answer

A. CO2, Glycine, and Glutamate

B. CO2, Gly, and N5-formimino tetrahydrofolate

C. Glutamine, Glycine, and CO2

D. CO2, Glutamate, and Glutamine

E. CO2, Glycine, and Glutamate

Answer 2

B. CO2, Gly, and N5-formimino tetrahydrofolate

CO2 contributes C6

Gly contibutes C4, C5, and N1(7)

N10 formyl-FH4 contributes C2 and C8

Gln amide contributes N3 and N9

Asp contributes N7 (1)

Question 3

What base is this?

A. Adenine

B. Guanine

C. Cytosine

D. Thymine

E. Uracil

Answer 3

B. Guanine

CO2 contributes C6

Gly contibutes C4, C5, and N1(7)

N10 formyl-FH4 contributes C2 and C8

Gln amide contributes N3 and N9

Asp contributes N7 (1)